Trinity Mirror chairman Sir Ian Gibson is to step down two months earlier than planned, as the troubled Daily Mirror publisher looks to speed up an overhaul of senior management.

Gibson, who has held the chairmanship since 4 May 2006, had intended to stand down on 2 August after delivering Trinity Mirror's interim financial results.

However the company announced on Friday that David Grigson, who was named a non-executive director and chairman designate on 1 January, will take up the role on 29 May.

Grigson had a key role in the dispute between the company and shareholders which ultimately resulted in Sly Bailey, the chief executive, announcing she is to stand down after a decade running the publisher of the Daily Mirror, Sunday Mirror, People and 140 regional newspapers.

Bailey is due to leave the company at the end of the year with Grigson leading the search for the new chief executive.

There has been speculation, which will be further fuelled by the quicker than expected handing of the reins to Grigson, that when a successor is found Bailey may leave the company earlier than planned.

Grigson said he is "looking forward to working more closely with the team".

Trinity Mirror said Gibson's early departure is to "enable a smooth transition" ahead of the company's interim results on 2 August.

"I have enjoyed working with the Trinity Mirror team and can see that with David Grisgon as chairman, they will continue to develop their strategy of maximising the benefits of a strong print portfolio while building a good range of digital businesses," said Gibson.

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